1. Field of the Invention
The present invention relates to wireless communication and, more particularly to a method and apparatus for improving capacity of channel in a wireless communication system.
2. Related Art
Wireless communication technology has been exponentially advancing with the development of high-level signaling schemes for efficient spectrum use. In turn, this necessitates settlements of the fundamental problems in communication and information theory, such as the capacity of physical channel over which the source and sink reliably transfers the information. The original concept of capacity, first developed by Claude E. Shannon in 1968, means the highest data rate in bits per channel use at which information can be sent with arbitrary low probability of error. From Shannon's channel coding theorem, the achievability of capacity of channel and the reliable encoder-decoder pairs have been widely studied with the problem of finding capacity of channel for various physical channel models. For a wideband communication link, the physical channel between the transmitter and receiver is generally modeled as the frequency-selective channel. Under the natural assumption that the noise process at the receiver front-end is modeled as wide-sense stationary (WSS) random process, it is well-known that the capacity of channel for wideband frequency selective channel can be achievable by the noise-whitening filter and the water-filling method.
In the interference channel, transmitters interferes non-desired receivers. If each transmitter use a linear filtering to transmit the signal, the interferences at the receivers can be modeled as wide-sense cyclo-stationary (WSCS) random process which has cycle period same as the sampling period of linear filtering. However, information theoretic result with WSCS interference or noise rarely exists.
It turns out that the tools needed to formulate the problem in a mathematically tractable form are the vectorized Fourier transform (VFT) and the matrix-valued-power spectrum density (MV-PSD). In some related literatures, the these tools have been used to design cyclic Wiener filters and linear receivers in a cyclo-stationary noise, and also used to find jointly optimal linear transmitter (Tx) and receiver (Rx) pairs, where the mean-squared error (MSE) at the output of the linear receiver is the objective to be minimized and the transmit waveform for linear modulation is found. However, no information-theoretic result has been derived yet using these tools.